The increasing further development of electromechanical power steering systems has resulted in the demands placed on the stability and reliability of such power steering systems steadily rising. An important requirement in this case is for a steering assistance function to be maintained even in the event of sensors and/or parts of the control system or parts of the electric motor failing.
DE10053818A1 discloses a solution in which a redundant servo motor is used, the said servo motor having two windings which are independent of one another and which are driven by two inverters which are independent of one another and, for their part, are driven by a redundant control arrangement, so that redundancy is ensured in the event of a fault. However, the proposed solution is very complicated since two independent control devices which are separate from one another are required.
JP20147784A likewise discloses a solution in which a servo motor is provided, the said servo motor having two windings which are independent of one another and which are driven by two inverters which are independent of one another, so that redundancy is ensured in the event of a fault. This solution is also relatively complicated.
Thus a need exists for an electromechanical power steering system that has improved redundancy behavior and is simple and cost-effective in terms of design.